Sensorless BLDC motor control with PIC microcontroller and mikroC

This post shows how to control a sensorless brushless DC (BLDC) motor using PIC16F887 microcontroller. The compiler used in this project is MikroElektronika mikroC PRO for PIC.

Basically there are two types of brushless motors: sensored and sensorless. Sensored BLDC motors come with three hall effect sensors which are used to detect (know) the position of the rotor (where it is located) at any moment, that’s why they called sensored.
The second type is: sensorless BLDC motors. Sensorless BLDC motor has no sensor to detect the rotor position, it has only 3 wires for power (3-phase). The commutation of sensorless BLDC motor is based on the BEMF (Back Electromotive Force) produced in the stator windings.

The main advantage of the sensorless BLDC motor control is lower system cost and the main disadvantage is the motor must be moving at minimum rate to produce sufficient BEMF to be sensed.

The following page contains a brief information about the BEMF technique:
Brushless DC motor control with PIC16F887 microcontroller

Components Required:

PIC16F887 microcontroller – datasheet
Brushless DC motor
6 x 06N03LA N-type mosfet (or equivalent) – datasheet
3 x IR2101 (or IR2101S) gate driver IC – datasheet
6 x 33k ohm resistor
3 x 10k ohm resistor
6 x 10 ohm resistor
3 x IN4148 diode
3 x 10uF capacitor
3 x 2.2uF capacitor
20 MHz crystal oscillator
2 x 22pF ceramic capacitor
10k ohm potentiometer
12V source
5V source
Breadboard
Jumper wires

Sensorless BLDC motor control with PIC16F887 circuit:
Project circuit schematic diagram is shown below.

All grounded terminals are connected together.

Sensorless BLDC motor control with PIC16F887 code:
The following C code is for mikroC PRO for PIC compiler. Configuration words are:
CONFIG1 = 0x2CD2
CONFIG2 = 0x0700

Timer2 module is configured to give a PWM signal with frequency of 19.53 KHz and resolution of 10 bits (prescaler = 1 and preload value = 255).
PWM frequency and resolution can be calculated using the functions below (Fosc = 20 MHz):
PWM_freqency = Fosc/{[(PR2) + 1] * 4 * (TMR2 Prescaler Value)} = 19.53 KHz
Resolution = log[4(PR2 + 1)]/log(2) = 10 bits

mikroC PRO for PIC code:

/**************************************************************************************

  Sensorless brushless DC ( BLDC ) motor control with PIC16F887 microcontroller
  C Code for mikroC PRO for PIC compiler
  Crystal oscillator used @ 20MHz
  Configuration words: CONFIG1 = 0x2CD2
                       CONFIG2 = 0x0700
  This is a free software with NO WARRANTY.
  http://simple-circuit.com/

***************************************************************************************/


#define PWM_MIN_DUTY      80
#define PWM_START_DUTY    200

#include <stdint.h>

void AH_BL();
void AH_CL();
void BH_CL();
void BH_AL();
void CH_AL();
void CH_BL();
void bldc_move();

uint8_t bldc_step = 0;
uint16_t motor_speed, i, j;

void Interrupt()
{
  // BEMF debounce
  int8_t j;
  for(j = 0; j < 10; j++) {
    if(bldc_step & 1) {
      if(!C1OUT_bit)    j -= 1;
    }
    else {
      if(C1OUT_bit)     j -= 1;
    }
  }
  bldc_move();
  C1ON_bit = 1;      // clear the mismatch condition
  C1IF_bit = 0;      // Clear comparator 1 interrupt flag bit
}

void bldc_move()        // BLDC motor commutation function
{
  switch(bldc_step){
    case 0:
      AH_BL();
      CM1CON0 = 0xA2;   // Sense BEMF C (pin RA3 positive, RB3 negative)
      break;
    case 1:
      AH_CL();
      CM1CON0 = 0xA1;   // Sense BEMF B (pin RA3 positive, RA1 negative)
      break;
    case 2:
      BH_CL();
      CM1CON0 = 0xA0;   // Sense BEMF A (pin RA3 positive, RA0 negative)
      break;
    case 3:
      BH_AL();
      CM1CON0 = 0xA2;   // Sense BEMF C (pin RA3 positive, RB3 negative)
      break;
    case 4:
      CH_AL();
      CM1CON0 = 0xA1;   // Sense BEMF B (pin RA3 positive, RA1 negative)
      break;
    case 5:
      CH_BL();
      CM1CON0 = 0xA0;   // Sense BEMF A (pin RA3 positive, RA0 negative)
      break;
  }
  bldc_step++;
  if(bldc_step >= 6)
    bldc_step = 0;
}

// set PWM1 duty cycle function
void set_pwm_duty(uint16_t pwm_duty)
{
  CCP1CON = ((pwm_duty << 4) & 0x30) | 0x0C;
  CCPR1L  = pwm_duty >> 2;
}

// main function
void main()
{

  ANSEL = 0x10;     // configure AN4 (RA5) pin as analog
  PORTD = 0;
  TRISD = 0;
  // ADC module configuration
  ADCON0 = 0xD0;    // select analog channel 4 (AN4)
  ADFM_bit = 0;

  INTCON = 0xC0;   // enable global and peripheral interrupts
  C1IF_bit = 0;    // clear analog coparator interrupt flag bit

  // PWM
  CCP1CON = 0x0C;  // configure CCP1 module as PWM with single output & clear duty cycle 2 LSBs
  CCPR1L  = 0;     // clear duty cycle 8 MSBs
  // Timer2 module configuration for PWM frequency of 19.53kHz & 10-bit resolution
  TMR2IF_bit = 0;  // clear Timer2 interrupt flag bit
  T2CON = 0x04;    // enable Timer2 module with presacler = 1
  PR2   = 0xFF;    // Timer2 preload value = 255

  // Motor start
  set_pwm_duty(PWM_START_DUTY);                 // Set PWM duty cycle
  i = 5000;
  while(i > 100)
  {
    j = i;
    while(j--) ;
    bldc_move();
    i = i - 50;
  }
  
  ADON_bit = 1;
  C1IE_bit = 1;   // enable analog coparator interrupt

  while(1)
  {
    GO_DONE_bit = 1;  // start analog-to-digital conversion
    delay_ms(50);     // wait 50 ms
    
    motor_speed = (ADRESH << 2) | (ADRESL >> 6); // read ADC registers
    
    if(motor_speed < PWM_MIN_DUTY)
      motor_speed = PWM_MIN_DUTY;
    set_pwm_duty(motor_speed);             // set PWM duty cycle
    
  }
  
}

void AH_BL()
{
  CCP1CON = 0;        // PWM off
  PORTD   = 0x08;
  PSTRCON = 0x08;     // PWM output on pin P1D (RD7), others OFF
  CCP1CON = 0x0C;     // PWM on
}

void AH_CL()
{
  PORTD = 0x04;
}

void BH_CL()
{
  CCP1CON = 0;        // PWM off
  PORTD   = 0x04;
  PSTRCON = 0x04;     // PWM output on pin P1C (RD6), others OFF
  CCP1CON = 0x0C;     // PWM on
}

void BH_AL()
{
  PORTD = 0x10;
}

void CH_AL()
{
  CCP1CON = 0;        // PWM off
  PORTD   = 0x10;
  PSTRCON = 0x02;     // PWM output on pin P1B (RD5), others OFF
  CCP1CON = 0x0C;     // PWM on
}

void CH_BL()
{
  PORTD = 0x08;
}

// End of code.

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/**************************************************************************************

Sensorless brushless DC ( BLDC ) motor control with PIC16F887 microcontroller

C Code for mikroC PRO for PIC compiler

Crystal oscillator used @ 20MHz

Configuration words: CONFIG1 = 0x2CD2

CONFIG2 = 0x0700

This is a free software with NO WARRANTY.

http://simple-circuit.com/

***************************************************************************************/

#define PWM_MIN_DUTY 80

#define PWM_START_DUTY 200

#include <stdint.h>

void AH_BL();

void AH_CL();

void BH_CL();

void BH_AL();

void CH_AL();

void CH_BL();

void bldc_move();

uint8_t bldc_step = 0;

uint16_t motor_speed, i, j;

void Interrupt()

{

// BEMF debounce

int8_t j;

for(j = 0; j < 10; j++) {

if(bldc_step & 1) {

if(!C1OUT_bit) j -= 1;

}

else {

if(C1OUT_bit) j -= 1;

}

bldc_move();

C1ON_bit = 1; // clear the mismatch condition

C1IF_bit = 0; // Clear comparator 1 interrupt flag bit

}

void bldc_move() // BLDC motor commutation function

{

switch(bldc_step){

case 0:

AH_BL();

CM1CON0 = 0xA2; // Sense BEMF C (pin RA3 positive, RB3 negative)

break;

case 1:

AH_CL();

CM1CON0 = 0xA1; // Sense BEMF B (pin RA3 positive, RA1 negative)

break;

case 2:

BH_CL();

CM1CON0 = 0xA0; // Sense BEMF A (pin RA3 positive, RA0 negative)

break;

case 3:

BH_AL();

CM1CON0 = 0xA2; // Sense BEMF C (pin RA3 positive, RB3 negative)

break;

case 4:

CH_AL();

CM1CON0 = 0xA1; // Sense BEMF B (pin RA3 positive, RA1 negative)

break;

case 5:

CH_BL();

CM1CON0 = 0xA0; // Sense BEMF A (pin RA3 positive, RA0 negative)

break;

}

bldc_step++;

if(bldc_step >= 6)

bldc_step = 0;

}

// set PWM1 duty cycle function

void set_pwm_duty(uint16_t pwm_duty)

{

CCP1CON = ((pwm_duty << 4) & 0x30) | 0x0C;

CCPR1L = pwm_duty >> 2;

}

// main function

void main()

{

ANSEL = 0x10; // configure AN4 (RA5) pin as analog

PORTD = 0;

TRISD = 0;

// ADC module configuration

ADCON0 = 0xD0; // select analog channel 4 (AN4)

ADFM_bit = 0;

INTCON = 0xC0; // enable global and peripheral interrupts

C1IF_bit = 0; // clear analog coparator interrupt flag bit

// PWM

CCP1CON = 0x0C; // configure CCP1 module as PWM with single output & clear duty cycle 2 LSBs

CCPR1L = 0; // clear duty cycle 8 MSBs

// Timer2 module configuration for PWM frequency of 19.53kHz & 10-bit resolution

TMR2IF_bit = 0; // clear Timer2 interrupt flag bit

T2CON = 0x04; // enable Timer2 module with presacler = 1

PR2 = 0xFF; // Timer2 preload value = 255

// Motor start

set_pwm_duty(PWM_START_DUTY); // Set PWM duty cycle

i = 5000;

while(i > 100)

{

j = i;

while(j--) ;

bldc_move();

i = i - 50;

}

ADON_bit = 1;

C1IE_bit = 1; // enable analog coparator interrupt

while(1)

{

GO_DONE_bit = 1; // start analog-to-digital conversion

delay_ms(50); // wait 50 ms

motor_speed = (ADRESH << 2) | (ADRESL >> 6); // read ADC registers

if(motor_speed < PWM_MIN_DUTY)

motor_speed = PWM_MIN_DUTY;

set_pwm_duty(motor_speed); // set PWM duty cycle

}

void AH_BL()

{

CCP1CON = 0; // PWM off

PORTD = 0x08;

PSTRCON = 0x08; // PWM output on pin P1D (RD7), others OFF

CCP1CON = 0x0C; // PWM on

}

void AH_CL()

{

PORTD = 0x04;

}

void BH_CL()

{

CCP1CON = 0; // PWM off

PORTD = 0x04;

PSTRCON = 0x04; // PWM output on pin P1C (RD6), others OFF

CCP1CON = 0x0C; // PWM on

}

void BH_AL()

{

PORTD = 0x10;

}

void CH_AL()

{

CCP1CON = 0; // PWM off

PORTD = 0x10;

PSTRCON = 0x02; // PWM output on pin P1B (RD5), others OFF

CCP1CON = 0x0C; // PWM on

}

void CH_BL()

{

PORTD = 0x08;

}

// End of code.

Finally this video shows a simple hardware circuit of the project:

IBUKUN OLUKANNI

September 27, 2023 at 7:03 am

Please, Am not good in programing,
Circuit can I use to replace the programmed in.
Thanks

Iyyanar

April 20, 2023 at 4:50 am

Getting error in mikroC while compiling the code, kindly share the correct code.

Marius

October 5, 2022 at 1:23 am

Trying to convert the code to MPLAB and I get Function Interrupt() is never used. How does this function get triggered?

12gustavo

February 16, 2022 at 12:45 am

Buenas tardes, excelente proyecto, felicitaciones. Disculpe, tengo una consulta, quizás me puede ayudar. Yo estoy implementando ese mismo proyecto pero con un LPC1769, este microcontrolador no posee la interrupción de comparación que usa usted, habrá alguna manera de hacer eso mismo sin interrupciones? Desde ya, muchas gracias.

nishad

January 17, 2022 at 9:36 am

what is the max voltage & current ratings for this driver ??

ferdinand

May 29, 2021 at 2:55 pm

If I use ir2104 as in the video, what modification should I do in the code? please help me

Sam

May 25, 2021 at 5:58 pm

Where i can get proteus bldc motor used in this simulation i am getting only sensord motor but i am not able to find sensorless motor in proteus.help me.

Sujit Ramesh Patil

May 25, 2021 at 5:56 pm

Can u make same for sensored bldc motor ?

SWAPAN SARKAR

April 5, 2021 at 10:06 am

Please explain the following function
CCP1CON = ((pwm_duty << 4) & 0x30) | 0x0C;

Ankit

February 26, 2021 at 1:52 pm

How can we control hall sensored BLDC motor.

stefan martin

January 17, 2021 at 11:43 am

The program work corect but the DEBOUNCING of feed back not work corect . the PWM high frecventi distorsion the EMF . I put 3x 100n cond paralel to 3x 10K resistor to filtrate the EMF. , and now work very nice.
I want in the future to add a START subrutine for start with mechanical load.
The second wish is to convert the code for PIC16F15344 or appropiate in 16F153xx family. Can you help me for this ?? the comparator module is diferent for this faamily.

Asim

December 6, 2020 at 7:55 am

Sir there is an error in mikroC while compiling the code. Ao i couldnt compile it. Plese let me know

enes

June 11, 2020 at 9:31 pm

I constructed all the circuits correct way, but when I give the power to the system, motors just making some sound and not turning. What should I do ?